SSPC-SP 5/NACE No. 1: White Metal Blast Cleaning Standard

COPYRIGHT © SSPC: THE SOCIETY FOR PROTECTIVE
COATINGS
This document and the information contained herein are copyrighted by
SSPC: The Society for Protective Coatings, 40 24th St 6th Fl, Pittsburgh PA
15222-4656 USA. All rights reserved.
You are granted the right to download an electronic file of this SSPC standard
for temporary storage on one computer for purposes of viewing and/or printing
a single copy for individual use. This copy may be may only be distributed
to other employees within your organization and only for information or
instructional purposes. Neither the electronic file nor the printed hard copy
may be reproduced or distributed in any other way without the express written
permission of SSPC.
DISCLAIMER
SSPC standards, guides, specifications, and other technical documents are
developed in accordance with voluntary consensus procedures established
by SSPC Technical Committees. They are intended to represent a balance of
interests, and are believed to represent good current practice. All documents
are monitored and revised as practices improve. Suggestions for revision are
welcome.
SSPC specifically disclaims responsibility for the use or misuse of any
information contained in this document, and is not responsible for the
application, interpretation, or administration of this information. Furthermore,
no person is authorized to issue an interpretation of this information on behalf
of SSPC. The supplying of details about patented formulations, treatments,
or processes is not to be regarded as conveying any right or permission to
the user of this document to use or sell any patented invention. When it is
known that the subject matter of the text is covered by patent, such patents
are reflected in the text. Mention of specific product names does not imply
SSPC endorsement.
It should be understood by all persons using this product that SSPC does not
give any warranties, expressed or implied, nor make any representations as
to the accuracy, completeness or usefulness of the information or conclusions
contained herein, nor assume any responsibility of any nature from whatever
cause including negligence resulting from the use of this product.
SSPC-SP 5/NACE No. 1
September 1, 2000
Editorial Revisions November 1, 2004
SSPC: The Society for Protective Coatings
JOINT SURFACE PREPARATION SPECIFICATION
SSPC-SP 5/NACE NO. 1
White Metal Blast Cleaning
This SSPC: The Society for Protective Coatings and NACE
International standard represents a consensus of those individual members who have reviewed this document, its scope
and provisions. Its acceptance does not in any respect preclude
anyone, having adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or
procedures not in conformance with this standard. Nothing
contained in this standard is to be construed as granting any
right, by implication or otherwise, to manufacture, sell, or use in
connection with any method, apparatus, or product covered by
Letters Patent, or as indemnifying or protecting anyone against
liability for infringement of Letters Patent. This standard represents minimum requirements and should in no way be interpreted
as a restriction on the use of better procedures or materials.
Neither is this standard intended to apply in all cases relating
to the subject. Unpredictable circumstances may negate the
usefulness of this standard in specific instances. SSPC and
NACE assume no responsibility for the interpretation or use
of this standard by other parties and accept responsibility for
only those official interpretations issued by SSPC or NACE in
accordance with their respective governing procedures and
policies, which preclude the issuance of interpretations by
individual volunteers.
©SSPC: The Society for Protective Coatings
40 24th Street, Sixth Floor
Pittsburgh, PA 15222
(telephone +1 412/281-2331)
©NACE International
1440 South Creek
Houston, TX 77084-4906
(telephone +1 281/228-6200)
Foreword
This joint standard covers the use of blast cleaning abrasives to achieve a defined degree of cleaning of steel surfaces
prior to the application of a protective coating or lining system.
This standard is intended for use by coating or lining specifiers,
applicators, inspectors, or others whose responsibility it may
be to define a standard degree of surface cleanliness.
The focus of this standard is white metal blast cleaning.
Near-white metal blast cleaning, commercial blast cleaning,
industrial blast cleaning and brush-off blast cleaning are addressed in separate standards.
Users of this standard are responsible for reviewing appropriate health, safety, and regulatory documents and for
determining their applicability in relation to this standard prior
to its use. This SSPC/NACE standard may not necessarily address all potential health and safety problems or environmental
hazards associated with the use of materials, equipment and/or
operations detailed or referred to within this standard. Users of
this standard are also responsible for establishing appropriate
health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities, if necessary,
to achieve compliance with any existing applicable regulatory
requirements prior to the use of this standard.
White metal blast cleaning provides a greater degree of
cleaning than near-white blast cleaning (SSPC-SP 10/NACE
No. 2).
The difference between a white metal blast and a nearwhite blast is that a white metal blast removes all of the coating, mill scale, rust, oxides, corrosion products, and other
foreign matter from the surface. Near-white blasting allows
light shadows, slight streaks, or minor discolorations caused
by stains of rust, stains of mill scale, or stains of previously
applied coating to remain on no more than 5 percent of each
unit area of surface.
CAUTIONARY NOTICE: SSPC/NACE standards are subject to periodic review and may be revised or withdrawn at any
time without prior notice. SSPC and NACE require that action
be taken to reaffirm, revise, or withdraw this standard no later
than five years from the date of initial publication. The user is
cautioned to obtain the latest edition. Purchasers may receive
current information on all standards and other publications by
contacting the organizations at the addresses below:
This joint standard was prepared by the SSPC/NACE Task
Group A on Surface Preparation by Abrasive Blast Cleaning.
This joint Task Group includes members of both the SSPC
Surface Preparation Committee and the NACE Unit Committee
T-6G on Surface Preparation (now STG 04).
2-61
SSPC-SP 5/NACE No. 1
September 1, 2000
Editorial Revisions November 1, 2004
1. General
3. Referenced Standards
1.1 This joint standard covers the requirements for white
metal blast cleaning of unpainted or painted steel surfaces
by the use of abrasives. These requirements include the end
condition of the surface and materials and procedures necessary to achieve and verify the end condition.
3.1 The latest issue, revision, or amendment of the referenced standards in effect on the date of invitation to bid shall
govern, unless otherwise specified.
3.2 If there is a conflict between the requirements of
any of the cited referenced standards and this standard, the
requirements of this standard shall prevail.
1.2 The mandatory requirements are described in Sections 1 to 9 as follows:
Section 1
General
Section 2
Definition
Section 3
Referenced Standards
Section 4
Procedures Before Blast Cleaning
Section 5
Blast Cleaning Methods and Operation
Section 6
Blast Cleaning Abrasives
Section 7
Procedures Following Blast Cleaning
and Immediately Prior to Coating
Section 8
Inspection
Section 9
Safety and Environmental Requirements
3.3 SSPC: THE SOCIETY FOR PROTECTIVE COATINGS STANDARDS:
AB 1
AB 2
AB 3
PA Guide 3
SP 1
VIS 1
NOTE: Section 10, “Comments” and Appendix A, “Explanatory
Notes” are not mandatory requirements of this standard.
Mineral and Slag Abrasives
Cleanliness of Recycled Ferrous
Metallic Abrasives
Ferrous Metallic Abrasives
A Guide to Safety in Paint Application
Solvent Cleaning
Guide and Reference Photographs
for Steel Surfaces Prepared by Dry
Abrasive Blast Cleaning
2. Definition
4. Procedures Before Blast Cleaning
2.1 A white metal blast cleaned surface, when viewed
without magnification, shall be free of all visible oil, grease,
dust, dirt, mill scale, rust, coating, oxides, corrosion products,
and other foreign matter.
4.1 Before blast cleaning, visible deposits of oil, grease,
or other contaminants shall be removed in accordance with
SSPC-SP 1 or other agreed upon methods.
4.2 Before blast cleaning, surface imperfections such as
sharp fins, sharp edges, weld spatter, or burning slag should
be removed from the surface to the extent required by the
procurement documents (project specification). Additional
information on surface imperfections is available in Section
A.5 of Appendix A.
2.2 Acceptable variations in appearance that do not affect
surface cleanliness as defined in Section 2.1 include variations
caused by type of steel, original surface condition, thickness of
the steel, weld metal, mill or fabrication marks, heat treating,
heat affected zones, blasting abrasives, and differences due
to blasting technique.
4.3 If a visual standard or comparator is specified to
supplement the written standard, the condition of the steel
prior to blast cleaning should be determined before the blasting
commences. Additional information on visual standards and
comparators is available in Section A.4 of Appendix A.
2.3 When a coating is specified, the surface shall be
roughened to a degree suitable for the specified coating system.
2.4 Immediately prior to coating application, the entire
surface shall comply with the degree of cleaning specified
herein.
5. Blast Cleaning Methods and Operation
5.1 Clean, dry compressed air shall be used for nozzle
blasting. Moisture separators, oil separators, traps, or other
equipment may be necessary to achieve this requirement.
2.5 SSPC-VIS 1 may be specified to supplement the written definition. In any dispute, the written standards shall take
precedence over visual standards and comparators. Additional
information on visual standards and comparators is available
in Section A.4 of Appendix A.
5.2 Any of the following methods of surface preparation
may be used to achieve a white metal abrasive blast cleaned
surface:
2-62
SSPC-SP 5/NACE No. 1
September 1, 2000
Editorial Revisions November 1, 2004
5.2.1 Dry abrasive blasting using compressed air, blast
nozzles, and abrasive.
air, vacuum cleaning, or other methods agreed upon by those
responsible for establishing the requirements and those responsible for performing the work. NOTE: The presence of
toxic metals in the abrasives or paint being removed may place
restrictions on the methods of cleaning permitted. Comply with
all applicable regulations. Moisture separators, oil separators,
traps, or other equipment may be necessary to achieve clean,
dry air.
5.2.2 Dry abrasive blasting using a closed-cycle, recirculating abrasive system with compressed air, blast nozzle,
and abrasive, with or without vacuum for dust and abrasive
recovery.
5.2.3 Dry abrasive blasting using a closed cycle, recirculating abrasive system with centrifugal wheels and abrasive.
7.3 After blast cleaning, surface imperfections that remain
(e.g., sharp fins, sharp edges, weld spatter, burning slag, scabs,
slivers, etc.) shall be removed to the extent required in the
procurement documents (project specification). Any damage
to the surface profile resulting from the removal of surface
imperfections shall be corrected to meet the requirements of
Section 2.4. NOTE: Additional information on surface imperfections is contained in Section A.5 of Appendix A.
5.3 Other methods of surface preparation (such as wet
abrasive blasting) may be used to achieve a white metal
blast cleaned surface by mutual agreement between those
responsible for performing the work and those responsible for
establishing the requirements. NOTE: Information on the use
of inhibitors to prevent the formation of rust immediately after
wet blast cleaning is contained in Section A.9 of Appendix A.
7.4 Any visible rust that forms on the surface of the steel
after blast cleaning shall be removed by recleaning the rusted
areas to meet the requirements of this standard before coating. NOTE: Information on rust-back (re-rusting) and surface
condensation is contained in Sections A.6, A.7, and A.8 of
Appendix A.
6. Blast Cleaning Abrasives
6.1 The selection of abrasive size and type shall be
based on the type, grade, and surface condition of the steel
to be cleaned, type of blast cleaning system employed, the
finished surface to be produced (cleanliness and roughness),
and whether the abrasive will be recycled.
8. Inspection
6.2 The cleanliness and size of recycled abrasives shall
be maintained to ensure compliance with this specification.
8.1 Work and materials supplied under this standard are
subject to inspection by a representative of those responsible
for establishing the requirements. Materials and work areas
shall be accessible to the inspector. The procedures and times
of inspection shall be as agreed upon by those responsible
for establishing the requirements and those responsible for
performing the work.
6.3 The blast cleaning abrasive shall be dry and free of
oil, grease, and other contaminants as determined by the test
methods found in SSPC-AB 1, AB 2, and AB 3.
6.4 Any limitations on the use of specific abrasives, the
quantity of contaminants, or the degree of allowable embedment shall be included in the procurement documents (project
specification) covering the work, because abrasive embedment
and abrasives containing contaminants may not be acceptable
for some service requirements. NOTE: Additional information
on abrasive selection is given in Section A.2 of Appendix A.
8.2 Conditions not complying with this standard shall be
corrected. In the case of a dispute, an arbitration or settlement
procedure established in the procurement documents (project
specification) shall be followed. If no arbitration or settlement
procedure is established, then a procedure mutually agreeable
to purchaser and supplier shall be used.
7. Procedures Following Blast Cleaning and
Immediately Prior to Coating
8.3 The procurement documents (project specification)
should establish the responsibility for inspection and for any
required affidavit certifying compliance with the specification.
7.1 Visible deposits of oil, grease, or other contaminants
shall be removed according to SSPC-SP 1 or another method
agreed upon by those parties responsible for establishing
the requirements and those responsible for performing the
work.
9. Safety and Environmental Requirements
9.1 Because abrasive blast cleaning is a hazardous operation, all work shall be conducted in compliance with applicable
occupational and environmental health and safety rules and
regulations.
7.2 Dust and loose residues shall be removed from
prepared surfaces by brushing, blowing off with clean, dry
2-63
SSPC-SP 5/NACE No. 1
September 1, 2000
Editorial Revisions November 1, 2004
10. Comments
of impact, hardness of the surface, amount of recycling, and the
proper maintenance of working mixtures of grit and/or shot.
The allowable minimum/maximum height of profile is usually dependent upon the thickness of the coating to be applied.
Large particle sized abrasives (particularly metallic) can produce
a profile that may be too deep to be adequately covered by a
single thin film coat. Accordingly, it is recommended that the
use of larger abrasives be avoided in these cases. However,
larger abrasives may be needed for thick film coatings or to
facilitate removal of thick coatings, heavy mill scale, or rust.
If control of profile (minimum/maximum) is deemed to be significant to coating performance, it should be addressed in the
procurement documents (project specification). Typical profile
heights achieved with commercial abrasive media are shown
in Table 5 of the Surface Preparation Commentary (SSPC-SP
COM). Surface profile should be measured in accordance with
NACE Standard RP0287 (latest edition), “Field Measurement
of Surface Profile of Abrasive Blast Cleaned Steel Surfaces
Using Replica Tape,” or ASTM(1) D 4417 (latest edition), “Test
Method for Field Measurement of Surface Profile of Blast
Cleaned Steel.”
10.1 Additional information and data relative to this standard
are contained in Appendix A. Detailed information and data are
presented in a separate document, SSPC-SP COM, “Surface
Preparation Commentary.” The recommendations contained
in Appendix A and SSPC-SP COM are believed to represent
good practice, but are not to be considered requirements of the
standard. The sections of SSPC-SP COM that discuss subjects
related to white metal blast cleaning are listed below.
Subject
Commentary Section
Abrasive Selection ............................................ 6
Film Thickness ................................................ 10
Wet Abrasive Blast Cleaning .......................... 8.2
Maintenance Repainting ................................ 4.2
Rust-back (Re-rusting) ................................... 4.5
Surface Profile ................................................ 6.2
Visual Standards ..............................................11
Welds and Weld Spatter .............................. 4.4.1
Appendix A. Explanatory Notes
A.4 VISUAL STANDARDS: Note that the use of visual
standards or comparators in conjunction with this standard is
required only when specified in the procurement document
(project specification) covering the work. However, it is strongly
recommended that the procurement document require the use
of visual standards or comparators. SSPC-VIS 1 provides color
photographs for the various grades of surface preparation as a
function of the initial condition of the steel. The series A SP 5,
B SP 5, C SP 5, D SP 5 and G SP 5 depict surfaces cleaned
to white metal grade. In addition, the series A-SP 5 M and N
depict surfaces cleaned by various metallic and non-metallic
abrasives to SP 5 condition. Other available visual standards
are described in Section 11 of SSPC-SP COM.
A.1 FUNCTION: White metal blast cleaning (SSPC-SP
5/NACE No. 1) provides the greatest degree of cleaning. It
should be used when the highest degree of blast cleaning
is required. The primary functions of blast cleaning before
coating are: (a) to remove material from the surface that can
cause early failure of the coating system and (b) to obtain a
suitable surface roughness and to enhance the adhesion of
the new coating system. The hierarchy of blasting standards is
as follows: white metal blast cleaning, near-white blast cleaning, commercial blast cleaning, industrial blast cleaning, and
brush-off blast cleaning.
A.2 ABRASIVE SELECTION: Types of metallic and nonmetallic abrasives are discussed in the Surface Preparation
Commentary (SSPC-SP COM). It is important to recognize that
blasting abrasives may become embedded in or leave residues
on the surface of the steel during preparation. While normally
such embedment or residues are not detrimental, care should
be taken to ensure that the abrasive is free from detrimental
amounts of water-soluble, solvent-soluble, acid-soluble, or
other soluble contaminants (particularly if the prepared steel is
to be used in an immersion environment). Criteria for selecting
and evaluating abrasives are given in SSPC-AB 1, “Mineral
and Slag Abrasives,” SSPC-AB 2, “Cleanliness of Recycled
Ferrous Metallic Abrasives,” and SSPC-AB 3, “Ferrous Metallic
Abrasives.”
A.5 SURFACE IMPERFECTIONS: Surface imperfections can cause premature failure when the service is severe.
Coatings tend to pull away from sharp edges and projections,
leaving little or no coating to protect the underlying steel. Other
features that are difficult to properly cover and protect include
crevices, weld porosities, laminations, etc. The high cost of
the methods to remedy surface imperfections requires weighing the benefits of edge rounding, weld spatter removal, etc.,
versus a potential coating failure.
Poorly adhering contaminants, such as weld slag residues,
loose weld spatter, and some minor surface laminations may
be removed during the blast cleaning operation. Other surface
defects (steel laminations, weld porosities, or deep corrosion
pits) may not be evident until the surface preparation has been
completed. Therefore, proper planning for such surface repair
work is essential because the timing of the repairs may occur
before, during, or after the blast cleaning operation. Section
4.4 of SSPC-SP COM and NACE Standard RP0178 (latest
A.3 SURFACE PROFILE: Surface profile is the roughness
of the surface which results from abrasive blast cleaning. The
profile depth (or height) is dependent upon the size, shape,
type, and hardness of the abrasive, particle velocity and angle
(1)
ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.
2-64
SSPC-SP 5/NACE No. 1
September 1, 2000
Editorial Revisions November 1, 2004
A.9 WET ABRASIVE BLAST CLEANING: Steel that
is wet abrasive blast cleaned may rust rapidly. Clean water
should be used for rinsing. It may be necessary that inhibitors
be added to the water or applied to the surface immediately
after blast cleaning to temporarily prevent rust formation.
The use of inhibitors or the application of coating over slight
discoloration should be in accordance with the requirements
of the coating manufacturer. CAUTION: Some inhibitive treatments may interfere with the performance of certain coating
systems.
edition), “Fabrication Details, Surface Finish Requirements,
and Proper Design Considerations for Tanks and Vessels to
be Lined for Immersion Service” contain additional information
on surface imperfections.
A.6 CHEMICAL CONTAMINATION: Steel contaminated with soluble salts (e.g., chlorides and sulfates) develops
rust-back rapidly at intermediate and high humidities. These
soluble salts can be present on the steel surface prior to blast
cleaning as a result of atmospheric contamination. In addition,
contaminants can be deposited on the steel surface during
blast cleaning if the abrasive is contaminated. Therefore,
rust-back can be minimized by removing these salts from
the steel surface and eliminating sources of recontamination
during and after blast cleaning. Wet methods of removal are
described in SSPC-SP 12/NACE No. 5. Identification of the
contaminants along with their concentrations may be obtained
from laboratory and field tests as described in SSPC-TU 4,
“Field Methods for Retrieval and Analysis of Soluble Salts on
Substrates.”
A.10 FILM THICKNESS: It is essential that ample coating
be applied after blast cleaning to adequately cover the peaks
of the surface profile. The dry film thickness of the coating
above the peaks of the profile should equal the thickness
known to be needed for the desired protection. If the dry film
thickness over the peaks is inadequate, premature rust-through
or failure will occur. To assure that coating thicknesses are
properly measured the procedures in SSPC-PA 2 (latest edition), “Measurement of Dry Coating Thickness with Magnetic
Gauges” should be used.
A.7 RUST-BACK: Rust-back (re-rusting) occurs when
freshly cleaned steel is exposed to moisture, contamination,
or a corrosive atmosphere. The time interval between blast
cleaning and rust-back will vary greatly from one environment to another. Under mild ambient conditions, if chemical
contamination is not present (see Section A.6), it is best to
blast clean and coat a surface the same day. Severe conditions may require more expedient coating application to avoid
contamination from fallout. Chemical contamination should be
removed prior to coating (see Section A.6).
A.11 MAINTENANCE AND REPAIR PAINTING: When
this standard is used in maintenance painting, specific instructions should be given on the extent of surface to be blast
cleaned or spot blast cleaned to this degree of cleanliness.
In these cases, the cleaning shall be performed across the
entire area specified. For example, if all weld seams are to be
cleaned in a maintenance operation, this degree of cleaning
shall be applied 100% to all weld seams. If the entire structure
is to be prepared, this degree of cleaning shall be applied
to 100% of the entire structure. SSPC-PA Guide 4 (latest
edition), “Guide to Maintenance Repainting with Oil Base or
Alkyd Painting Systems,” provides a description of accepted
practices for retaining old sound coating, removing unsound
coating, feathering, and spot cleaning.
A.8 DEW POINT: Moisture condenses on any surface
that is colder than the dew point of the surrounding air. It is,
therefore, recommended that the temperature of the steel
surface be at least 3 °C (5 °F) above the dew point during dry
blast cleaning operations. It is advisable to visually inspect
for moisture and periodically check the surface temperature
and dew point during blast cleaning operations and to avoid
the application of coating over a damp surface.
2-65